The new crimes allegedly occurred while she was being held in Orange County jail

The Florida woman already charged in the murder of her 80-year-old mother-in-law in Clarkstown has been indicted on charges she plotted from jail to kill key witnesses against her.

Prosecutors say Diana Nadell solicited a fellow inmate to arrange the murder of two witnesses prepared to testify against her in Peggy Nadell's slaying.

The targets were not named by investigators.

Three other women have already pleaded guilty to felony charges in the case, with one of them saying she participated directly in the killing. Andrea Benson, 25, of Washington, D.C., is being held in the Rockland County jail after pleading guilty to murder; the other two alleged co-conspirators are free pending sentencing.

"These are disturbing allegations in an already shocking case," Rockland County District Attorney Thomas Zugibe said in a statement.

Clarkstown police and prosecutors say Diana Nadell killed her mother-in-law to get her hands on her husband's share of Peggy Nadell's more than $3 million estate.

Diana Nadell was charged with first-degree murder in the stabbing and beating death of her mother-in-law Peggy Nadell during an arraignment in Clarkstown Town Court. (Video by Seth Harrison/The Journal News)

Peggy Nadell's children — Susanne Nadell-Scaccio of Airmont and James Nadell, 52, a Florida neuropsychologist — share the estate. James Nadell, Diana Nadell's husband, is not a suspect and has not responded to requests for comment.

Diana Nadell is being held in the Orange County jail after being transferred, at her lawyer's request, from Rikers Island in the Bronx. She has pleaded not guilty to first-degree murder, which carries a life sentence without parole.

She has been kept separate from Benson, who said in court that she choked Peggy Nadell with a pocketbook strap before Diana Nadell bashed her mother-in-law with a solid object then stabbed her multiple times.

Benson, a distant cousin of Diana Nadell, said Diana Nadell had promised her $10,000 to help her kill Peggy Nadell. Prosecutors say the pair drove to New York together from Washington and committed the murder in the early morning. Peggy Nadell's daughter found her dead hours later with a knife in her chest.

Joyner said she provided Diana Nadell with an alibi by making telephone calls from Washington with the Florida woman's cellphone. Grant, a cousin of Nadell, said she helped bring all the women together after being recruited by a relative in Jamaica.

Zugibe said in a news release that the Orange County inmate Diana Nadell allegedly solicited to assist in killing the two witnesses was someone Nadell "believed was being deported to Jamaica." .

The new charges against Diana Nadell are two counts of conspiracy in the second degree, two counts of intimidating a witness in the first degree, two counts of attempted tampering with a witness in the first degree, and two counts of criminal solicitation in the second degree.

The investigation was conducted by the Clarkstown Police Department, Rockland County District Attorney's Office, Orange County Sheriff's Department and Orange County District Attorney's Office, Zugibe said.

"This office will do everything in its power to vigorously prosecute those who seek to intimidate and harm witnesses," Zugibe said. "This new indictment underscores the lengths our law enforcement partners will go to ensure public safety — on both sides of the jail bars."